Digital elevation model (DEM), as the essential sources of GIS, has become an important part of a national spatial data infrastructure (SDI) in many countries, under the umbrella of digital geospatial data framework (DGDF) .

• 数字高程模型(Digital Elevation Model,DEM)作为GIS重要的数据来源,已成为国家空间数据基础设施(National Spatial Data Infrastructure,NSDI)的基础内容之一,并被纳入到数字化空间框架(Digital Geospatial Data Framework,DGDF)进行规模化生产。